1. Field of the Invention
This invention relates in general to underwater launching of missiles from submarines, and more particularly but without limitation thereto to apparatus for controlling the underwater trajectory of missiles by selectively venting gas from the missile interior out to regions in the water flowing over the missile exterior that would otherwise be at a lower pressure.
2. Information
A commonly used technique for launching a missile from a submerged submarine involves admitting pressurized gas into the submarine launch tube containing the missile sufficiently to both overcome the static water pressure head and propel the missile upward with such an initial velocity as to cause the missile to breach the water surface and travel beyond up into the atmosphere, after which the primary rocket motor ignites.
If the rocket motor of the ejected missile does not ignite, there is a risk that the missile will strike the submarine as it falls back into the water.
If a missile is launched from a moving submarine, the relative motion between the submarine and the water (crossflow) causes hydrodynamic forces to be exerted on the missile, causing it to pitch backwards as it emerges from the launch tube and risk striking the wall of the launch tube. Consequently, launch tubes may be provided with resilient linings which allow missile contact in order to exert forces for counteracting the hydrodynamically induced forces; however the missile structure must be made stronger and heavier in order to withstand such contact forces. Alternatively, the launch tubes may be made large enough to accommodate the missile sideways movement, but this can result in excessively large tubes and insufficient control of missile attitude.
Consequently a long-felt need exists for a way to exert side forces and/or moments on an underwater-launched missile both as it emerges from the submarine launch tube and during the underwater course of travel from the launch tube to the surface. The present invention is directed toward reducing the foregoing risks and satisfying the need, using apparatus to selectively vent gas from within the missile interior out to low pressure regions in the water flowing over the missile exterior.